Providing multicast service to mobile hosts is difficult due to frequent changes of mobile host location and group membership. To overcome the difficulty, several multicast protocols for mobile hosts have been proposed. Although the protocols solve several problems inherent in multicast routing proposals for static hosts, they still have problems such as non-optimal delivery path, datagram duplication, etc. In this paper, we summarize these problems of multicast routing protocols and propose an efficient multicast protocol using a multicast agent in wireless mobile networks, where a mobile host receives a tunneled multicast datagram from a multicast agent located in a network close to it or directly from the multicast router in the current network. While receiving a tunneled multicast datagram from a remote multicast agent, the local multicast agent starts multicast join process, which makes the multicast delivery route optimal. The proposed protocol reduces data delivery path length and decreases not only the amount of duplicate copies of multicast datagrams but also multicast traffic load. We examined and compared the performance of the proposed protocol and existing protocols by simulation under various environments and we got an improved performance over the existing proposals.